Previous row with LAG

sql

SELECT day,
       revenue,
       LAG(revenue) OVER (ORDER BY day) AS prev_revenue
FROM daily_revenue;

Explanation

`LAG` is the easiest way to compare the current row to the previous row.

Learn the surrounding workflow

Compare similar commands or jump into common fixes when this command is part of a bigger troubleshooting path.

Same sheet · prioritizing LAG and LEAD basics

Avoid NULL on the first row.

Open In sheetsqlsame section

Preview the next value in sequence.

Open In sheetsqlsame section

Custom offset with LAG.

Open In sheetsqlsame section

Subtract the previous day's value.

Compute relative change versus previous row.

Measure time since the prior event.